1. Field of the Invention
This invention relates to a radiation detecting cassette having a radiation detector accommodated within a casing.
2. Description of the Related Art
In the field of radiography for medical diagnosis and the like, various solid-state radiation detectors (whose main part comprises semiconductors; hereinafter also simply referred to as “detectors”) which detect radiation penetrating an object and produce an image signal carrying radiographic image information of the object have recently been proposed and brought into actual use (see, for example, U.S. Pat. No. 6,268,614 hereinafter referred to as Patent Reference 1 and Japanese Unexamined Patent Publication No. 2000-284056 hereinafter referred to as Patent Reference 2). Various radiation detecting cassettes having a case accommodating therein such a solid-state radiation detector and the like have also been proposed (see, for example, U.S. Patent Laid-Open No. 20020014594 hereinafter referred to as Patent Reference 3 and Japanese Unexamined Patent Publication No. 2002-014170 hereinafter referred to as Patent Reference 4).
Such a radiation detecting cassette is relatively thin and made in portable size. This allows radiophotographing with a very high-degree of freedom. For example, even for a patient who cannot move, a radiophotograph can be taken by placing the radiation detecting cassette under a body part of the patient to be radiophotographed while keeping the patient on a bed, and then moving a radiation source of a radiation image information recording apparatus to a position on a side of the patient opposite the radiation detecting cassette.
One example of a specific construction of the radiation detecting cassette is a construction in which the solid-state radiation detector and an electric circuit board for processing a signal detected by the detector are secured to a frame located inside a casing of the cassette, and the solid-state radiation detector and the electric circuit board are connected with each other via a flexible circuit board.
In order to prevent breakage of the solid-state radiation detector accommodated within such a radiation detecting cassette, Patent Reference 4 proposes a radiation detecting cassette in which a shock absorber is positioned on an upper side (i.e., a side exposed to the radiation) of the solid-state radiation detector and a lower side of the solid-state radiation detector is secured to the frame. With this configuration, the solid-state radiation detector cannot move towards the bottom of the radiation detecting cassette. Therefore, if the solid-state radiation detector is subjected to a shock in the direction towards the bottom thereof, shock cannot be absorbed.
On the other hand, when elastomeric bodies such as rubber or gel are used to sandwich the solid-state radiation detector therebetween for supporting the upper and lower surfaces of the detector as proposed in Patent Reference 3 mentioned above, it is difficult to ensure the positional precision of the solid-state radiation detector within the casing because the elastic bodies tend to change the shape.